My batteries are sticker labeled "4400 mah", and have a silver rectangle where the turnigy logo is on the hobby king batteries, but otherwise look identical to the hobby king batteries. For a variety of reasons, I believe them to be the exact same batteries as HobbyKing sells as turnigy 6s2p 4500 mah LiFePo4, possibly even indirectly from hobby king.
I have two packs and have run 15 use cycles on them so far. I am keeping a log by editing the second post here:
http://endless-sphere.com/forums/viewtopic.php?f=3&t=46287
Both packs seem to consistently require less time to fully charge cell number 5 than the other cells. The longer I have them, the longer they hold the surface charge, but they still exhibit some behaviors I consider weird.
So far, bottom line facts are:
They haven't puffed that I can tell (stacked with HDPE and fiberglass taped).
I have not done a scientific test yet, but using the required recharge ah, and 2.7 v per cell loaded alarm level, it appears my weakest cells have around 3800 mah of capacity. I plan to test this now that the cells seem broken in (hold surface charge longer), but haven't made time yet.
Bellow about 90% SoC and with less than ~3.8 ah used, the resting voltage of all cells generally match each other.
Resting voltage only weakly correlates with SoC. For example, one time it took less mah to charge from 3.18v than from 3.2v another time.
The two cells that reach full charge fastest hold their surface charge longest, making me suspect they are the good cells, rather than the bad cells in this imbalance situation, but I haven't tested that will a deep discharge yet.
The imbalance resulting from a 50% discharge cycle is on the order of 200 mah.
Under an 8-10 amp load with two packs in series, the voltage sags by about 0.2v per cell initially. If I measure from 3.3v/cell and ignore the inconsistent resting voltage drop during discharge at different SoC points, the voltage under load drops as the SoC drops, in a nominally linear way. Thus with a repeatable but inaccurate cell level voltage alarm, I have started figuring out an alarm voltage level setting which correlates roughly with an SoC, but measuring resting voltages doesn't seem to work the same way. Maybe this can be partly chalked up to the definition of "resting" or inconsistent temperature, or something like that.
I stopped messing with ways of getting an alarm while there is still a residual charge because 1.) I got my throttle working somewhat properly, and turned on cruise control, and now I can make the round trip on less than 50% of the rated capacity. and 2.) I have a watt meter.
So that's what I know. I'll try to keep posting my guinea pig data as long as the cells live, 5 cycles a week when it is cold, probably less once it warms up. If they make it that far, I may buy more of them to make a bigger pack for the family bike.
